The asprete, (Romanichthys valsanicola Dumitrescu, Banarescu & Stoica, 1957) is an extremely endangered species, endemic to a Romanian river: Valsan. Romanichthys valsanicola is the fish genus having the smallest range in Eurasia and was considered by Maitland (1991) the most endangered freshwater fish species in Europe. Once Palearctic the asprete is now a preglaciar relict, which can be found in our days only in the river Valsan. Found in cold, clear, fast-flowing areas, hidden under rocks. Territorial. The asprete is a predator feeding exclusively on aquatic invertebrates: larvae of rheophilic insects, mainly mayflies and stoneflies.

As part of an ongoing study into the behaviour and ecology of asprete, eight radio-tagged asprete were tracked in the River Valsan, a central roumanian stream, from august 2004 to December 2004. Unfortunately two of them had been lost, and one was released, and his tracking was cancelled, due to his small size. The radio-tracking procedures were obstruct during July, August and November because of high rainfall who caused the River Valsan to flood repeatedly, with these floods being of unusual duration and severity.